1. Field of the Invention
This invention relates to an optical disc and a method for registering on a label side of the optical disc. More particularly, the label side has a plurality of turns of wobbled grooves connected in series to form a spiral track. Besides, the turns of wobbled grooves are provided to be the registering reference.
2. Description of the Prior Art
Recordable optical discs and rewritable optical discs have been widely adopted for storing data. However, it's not easy to know the information on the disk by eyes. Thus, to display stored information on the disk is an attractive feature.
Consumers always expect more convenient methods to recognize data, i.e., texts, images, or the like, recorded in their optical discs, methods capable of labeling on a label side (i.e. a non-data side or a top surface) of an optical disc have been continuously developed. Basic methods capable of labeling on the optical disc comprises writing on the label side of the optical disc with a permanent label maker (e.g. a sharpie maker) and sticking a printed paper sticker label on the label side of the optical disc. Other label methods performed in optical disc drivers comprise printing with ink jet, thermal wax transfer, thermal dye transfer, and the like. Additionally, lasers can be used in an optical disc driver for labeling on a disc. The aforesaid label methods are applicable for CD-R, CD+R, CD-RW, DVD-R, DVD+R, DVD-RW, and other types of optical discs.
Methods of writing an image on a label side of an optical disc are disclosed. However, to produce a track or other type of marking to assist in registering is an issue of labeling an image on a label side of an optical disc. Saw-teeth, triangles, or other reference marks pre-printed on a label side of an optical disc have been disclosed in U.S. patent application Ser. No. 10/347,074.
Please refer to FIG. 1. FIG. 1 is a schematic diagram illustrating a label side 10 of an optical disc 1 disclosed in prior art. The label side 10 of the optical disc 1 has a plurality of reference marks 100. As shown in FIG. 1, the reference marks 100 are pre-printed on the label side 100 of the optical disc 1. Referring to FIG. 1, a method of labeling an image on the optical disc 1 comprises the following steps. At first, a laser spot 18 emitted from an optical pick-up unit (not shown) is registered on an absolute radial position R0 of the label side 10 of the optical disc 1 according to the reference marks 100. Theoretically, the aforesaid step can be regarded as a return-to-zero step and a step of calibrating center-deviation. Afterward, the laser spot 18 is moved along a radial direction outside to a first radial position R1. Thereby, an image of a first track is written on the optical disc 1. Subsequently, the aforesaid steps are repeated. In other words, the laser spot 18 is moved outwardly along the radial direction, and the image of each of tracks is written on the optical disc 1 sequentially until a whole image is completed.
However, according to the registering method in the prior art, an optical pick unit sequentially writes the image of each of tracks in a concentric circle path on the label side 10. After the optical pick unit writes the image of a track, the position of the laser spot must be registered again on the next track. Thus, it takes from tens of minutes to half an hour in writing images on a label side for the labeling method in the prior art. Further, time consumption is a main disadvantage of the prior art.